Process for making metallic chromium



Patented Apr. 20, 1926.

UNITED STATES PATENT OFFICE.

WILLIAM E. S. STRONG AND CHARLES E. PARSONS, OF NEW YORK, N. Y., AND SAMUEL PEACOCK, OF WHEELING, WEST VIRGINIA, ASSIGNORS TO METAL RESEARCH COR- PORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

PROCESS'FOR MAKING METALLIC CHROMIUM.

No Drawing.

To all 211710121, it may concern:

Be it known that we, \Vnmnmr E. S.

Srnoxo, a citizen of the United States, residing at New York, in the county of New York and State of New York, CHARLES E. PAnscNs, a citizen of the United States, residing at New York, in the county of New York and State of New York, and SAMUEL PEACOCK, a citizen of the United States, residing at WVheeling, in the county of Ohio and State of Vest Virginia, have invented certain new and useful Improvements in Processes for Making Metallic Chromium; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appe-rtains to make and use the same.

This invention relates to a process for making metallic chromium in a shaft furnace of the type used in smelting ore, and has for its object to improve the procedures which have heretofore been proposed.

With this and other objects in view, the invention consists inthe novel steps and combinations of steps constituting the process all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

A modern iron ore smelting blast furnace with suitable equipment for blastheating, is capable of maintaining in its fusion zone a temperature of about 1600 C. in an atmosphere free from uncombined oxygen or carbon dioxide. According to this invention, the carbon in this zone of the furnace is maintained at a white heat, and under such conditions sodium. oxide or salts containing sodium oxide, are brought into contact with such white hot carbon whereupon they are readily reduced to elemental sodium and carbon monoxide. The sodium thus produced is vaporized instantly upon its formation and rises with the gases of the furnace until it is cooled to about 750 C. by contact with the relatively cold charge in the upper part of said furnace, where said vaporized sodium condenses. But as it is molten above 100 0., said sodium continually moves downward by gravity in the form of a liquid and heats up again until it is again vaporized. By this means, a high concentration of sodium vapor is maintained at or near the 750 0. line of the Application filed February 19, 1925. Serial No. 10,428.

furnace, with an increase of its partial. pressure. This effects an increase in the temperature necessary to vaporize the metal and a superheated state of the metal ensues.

Such heated liquid elemental sodium when in contact with chromium oxide will react as follows This reaction with the reagents at about 800 C. has an exothermic thermal balanceof about836 B. t. u. per pound of chromium made. This is an energy gain capable of adding over 400 C. to the temperature reaction involved and thereby it increases the velocity of the reaction. Of course, the carbon present immediately reduces the sodium oxide produced back to elemental sodium.

It has been observed. however, that the somewhat impure metallic chromium thus produced takes the liquid form somewhat above the 1200 C. line of the furnace, and in falling through the charge material to the hearth, it contacts more or less with the white hot carbon in the fusion zone, and

a small percentage of chromium carbide is formed. This carbide is decomposed by contact with the molten sodium present, but said molten sodium does not in any considerable mass extend much below the 1000 C. lineof the furnace. It has been found that by introducing into the furnace through the tuycres sodium. combined with oxygen, preferably in the form of sodium chromate, such chromium carbide as is formed is converted into sodium carbide and elemental chromium.

In the industrial operation of this process, an initial charge-consisting of chromium oxide, C1 0,, and an oxygen hearing sodium salt such as sodium carbonate and coke or charcoal is charged into the furnace in the usual manner of operating iron smelting blast furnaces and the metal is tapped from the hearth in the usual manner. Of course, chrome ores may be substituted for the above-mentioned chromic oxide. Although the slag formed is relatively small in quandueto slagging and losses at the throat of the furnace which are in the forms of car-- bides, cyanamids, etc: of sodium., If it is preferred to make good such losses, which amount approximately to 4% to 6%, the requisite amount of combined sodium is added through the tuyeres.

The advantages of this process reside in the ability to make metallic chromium at and carbon causing the sodium to be liberf ated, volatilized and to react with the chromic oxide present to produce the desired metallic chromium.

2. The process of making metallic chromium in a. blast furnace, which consists in smelting a mixture containing chromic oxide an oxygen bearing sodium compound 2nd carbon causingthe sodium to be liberted, Volatilized and its partial pressure increased, and to react with the chromic oxide present to produce the desired metallic chromium.

3. The process of making metallic chromium in a blast furnace, which consists in smelting a mixture containing chromic oxide, an oxygen bearing sodium compound and carbon causing the sodium to be liberated, volatilized and to react with the chromie oxide present to produce sodium oxide and the desired metallic chromium and causing the carbon to reduce said sodium oxide vWlLLIAH E. S STRONG. ,CHARLES E. PARSONS.

SAMUEL PEACOCK. 

